Reaction mass of aluminium chloride, iron dichloride, magnesium chloride and manganese dichloride

Endpoint summary

Additional information

The submission item is regarded as a multi-constituent substance. The main metal, i.e. iron, contributes less than 80% of the total metal molarity. The other main components, i.e. manganese, magnesium, and aluminium, contribute 10% or more. Magnesium is a bioessential metal, present in high natural background concentrations and very mobile. The same applies to the chloride anion (Bohn et al 1979). Both components are not considered in the present assessment of environmental fate and pathways, but the focus in this section is on iron and the main metals manganese and aluminium.

Environmental levels

Iron, manganese, and aluminium are naturally occurring elements that are present at considerable levels in all environmental media. Natural sources of iron, manganese, and aluminium tend to contribute more to the environmental occurrence of these elements than anthropogenic sources. The following table summarizes the levels considered as background concentrations in the present assessment. These background concentrations may be used in the environmental risk assessment.

Table: Medium concentrations used for Chemical Safety Assessment (CSA)

Metal species	Concentration in medium (upper level if range)
	Surface freshwater, dissolved		Freshwater sediment		Soil
	[µg/L]	Reference	[g/kg d.w.]	Reference	[g/kg d.w.]	Reference
Iron	66	Gaillardet et al 2003	20	Vangheluwe et al 2010	21	Vangheluwe et al 2010
Manganese	34*	Gaillardet et al 2003	1.26	Heiny & Tate 1997	0.55*	Donisa et al 2000 & WHO 2004
Aluminium	50	Jones & Bennett 1985	27	Vangheluwe et al 2010	30	Vangheluwe et al 2010

* considered as natural background concentration not influenced by anthropogenic sources

It should be noted that some of the figures may deviate from those in table A3.1 given in the SIAR 2007 (SIDS Initial Assessment Report for SIAM 24 OECD Paris, France, 17 -20 April 2007), which is given below in the iron section. Nonetheless the above listed environmental levels are in the ranges given in the SIAR (2007).

• Donisa C, Mocanu R, Steinnes E, Vasu A (2000). Heavy metal pollution by atmospheric transport in natural soils from the northern part of Eastern Carpathians. Water, Air and Soil Pollution: 120(3–):347–58
• ECHA European Chemicals Agency (2008) Guidance on information requirements and chemical safety assessment Appendix R.7.13-2: Environmental risk assessment for metals and metal compounds. 74 p
• Gaillardet J, ViersJ, Dupré B (2003). Trace elements in river waters. IN: Drever JI (Ed) Surface waters and Ground water, Weathering, and Soils, Treatise on Geochemistry. Vol 5 Elsevier ( Amsterdam), pp 225-272
• Heiny JS, Tate CM (1997). Concentration, distribution, and comparison of selected trace elements in bed sediment and fish tissue in the South Platte River Basin, USA, 1992–1993. Archives of Environmental Contamination and Toxicology 32:246 -59
• Jones KC & Bennett BG (1985). Exposure commitment assessments of environmental pollutants. London, University of London, King's College. Monitoring and Assessment Research Centre, MARC Technical Report 33, 33 pp
• Vangheluwe M, Vercaigne I, Vandenbroele M, Shtiza A, Heijerick D (2010). White Paper on exposure based waiving for iron and aluminium in soil and sediments. ARCHE, Stapelplein 70, Box 104, 9000 Gent, Belgium
• WHO World Health Organization (2004). Manganese and its Compounds: Environmental Aspects. Concise International Chemical Assessment Document 63, Corrigenda published by 12 April 2005 have been incorporated. Self-published, Geneva, Switzerland

Additional information on iron

Iron is the fourth most abundant element in the Earth's crust accounting for approximately 5% (by weight) (Wildermuth 2004). Iron is found in various minerals (as ferric chloride, ferrous chloride, ferric sulphate, ferrous sulphate and their mixtures, oxides and sulphides), and in nearly all soils, sediments and mineral waters. Iron levels range from 0.01 mg/L in seawater up to 0.1 – 10 mg/L in fresh water, 0.5 – 5% in soil and 1 – 9% in sediments (Drever 1982, Hem 1970, Horne 1978, Kabata-Pendias & Pendias 1984, Khalid et al 1977, Lindsay 1979, Morel 1993, Stumm & Morgan 1981). Overall, the data show that iron is present naturally in abundance in all environmental compartments, apart from water, where solubility of the hydroxide and oxides is a limiting factor. The dissolved concentrations of iron tend to be low whereas sediment concentrations can be high.

Table: Summary of background concentrations from SIAR 2007 (SIDS Initial Assessment Report for SIAM 24 OECD Paris, France, 17-20 April 2007)

Matrix or organism	Typical concentration (order of magnitude only)
Earth’s crust	5%
Soil	Approx. 5%*
Atmosphere – background	1 ng/m³
Atmosphere - urban	6000 ng/m³
Sediment – fresh water and marine	4.5% d.w.*
River water – background	Approx. 1 mg/L (total)
Sea water – background	Approx. 10 µg/L, as hydroxide
Plants – roots	4000 mg/kg d.w.
Plants	200 mg/kg d.w.
Marine sediment organisms	Up to approx. 500 mg/kg d.w.
Marine algae	Up to approx. 500 mg/kg d.w.
Marine crustacean	Up to approx. 500 mg/kg d.w.
Gastropods	Up to approx. 500 mg/kg d.w.
Marine fish	5 – 30 mg/kg d.w.
Terrestrial animals	Typically up to 600 mg kg d.w.

* Values deviate from those to be used in the chemical safety assessment given above

• Drever JI (1982). The geochemistry of natural waters; Prentice-Hall, Englewood Cliffs, NJ, U.S.A.
• Hem JD (1970). Study and interpretation of the chemical characteristics of natural water, 2nd ed.
• Horne RA (1978). The Chemistry of our Environment. John Wiley and Sons, New York.
• Kabata-Pendias A, Pendias H (1984). Trace elements in soils and plants; CRC Press, Boca Raton, FL, U.S.A.
• Khalid RA, Gambrell RP, Verloo MG, Patrick WH (1977). Transformations of heavy metals and plant nutrients in dredged sediments as affected by oxidation reduction potential and pH; U.S. Army contract N DACW39-74-C-0076.
• Lindsay WL (1979) Chemical equilibria in soils; John Wiley and Sons, New York.
• Morel FMM (1983) Principles of aquatic chemistry; John Wiley and Sons, New York.
• Stumm W, Morgan JJ (1981). Aquatic chemistry, 2nd ed.; John Wiley and Sons, New York.
• Wildermuth E, et al (2004). Iron compounds. IN: Bohnet M et al (Eds). Ullman's Encyclopedia of Industrial Chemistry. 7th Edition. Wiley, New York. Web-version, Release 2004.

Aquatic fate and pathways

The materials in the submission item readily convert to the naturally occurring metal species. They will integrate into the equilibrium system between the large sediment reservoirs and the dissolved species under environmental conditions. Biodegradation is not relevant as the submission item's constituents and their environmental transformation products are inorganic and thus a priori mineralized. No formation of organometallic species is anticipated. The submission item is transformed into naturally occurring inorganic, inert compounds after release to the aquatic environment. These compounds will fill the metal sinks of the sediment compartment with no significant influence on bioavailability.

General considerations with regard to iron and manganese in sediments

The following two sections are taken from the Metal Environmental Risk Assessment guidance document (ICMM 2007) as they show that iron and manganese are generally considered to contribute to metal detoxication in the environment rather than causing toxic effects.

Simultaneously Extracted Metal – Acid Volatile Sulfides (SEM-AVS) concept

In anoxic sediments, sulfide produced by sulfate reduction reacts with Fe2+ and Mn2+ ions to form insoluble iron and manganese sulfides such as amorphous iron sulfide, mackinawite, greigite, pyrrthotite, troilite, pyrite and pink and green manganese sulfides (Wang and Chapman 1999).

Although pyritic sulfide phases are both abundant and reactive towards trace metals, iron monosulfides, quite often referred to as ‘Acid Volatile Sulfides’ (AVS), are considered to be a more reactive sulfide pool (ICMM 2007).

Di Toro et al. (1990, 1991) have proposed an SEM/AVS Model based on the recognition that AVS is a reactive pool of solid phase sulfide available to bind to metals, forming insoluble metal-sulfide complexes that are non-bioavailable while releasing Mn+2 and Fe+2 ions (ICMM 2007).

Fe/Mn (oxy)hydroxides

Although sulfides have been identified as a main factor for buffering the bioavailability of metals in (anoxic) sediments, toxicity may still not be seen even if the sulfide pool becomes exhausted. This shows the importance of other binding phases, e.g. organic ligands and dissolved/colloidal Fe or Mn oxides (Müller and Sigg 1990), which in addition contribute to the reduction of metal bioavailability.

• Di Toro DM, Mahony JD, Hansen DJ, Scott KJ, Hicks MB, Mays SM, Redmond MS (1990). Toxicity of cadmium in sediments: the role of acid volatile sulfides. Environmental Toxicology and Chemistry 9:1487-1502.
• Di Toro DM, Mahony JD, Hansen DJ, Scott KJ, Carlson AR, Pesch CE (1991). Acid volatile sulfide predicts the acute toxicity of cadmium and nickel in sediments. Environmental Sci. Technol. 26:96-101.
• ICMM International Council of Mining and Metals (2007). MERAG: Metals Environmental Risk Assessment Guidance. Self-published London, UK. ISBN: 978-0-9553591-2-5. 80 p
• Müller B, Sigg L (1990). Interaction of trace metals with natural particle surfaces: comparison between adsorption experiments and field measurements. Aquat.Sci. 51, 75-92
• Wang FY, Chapman PM (1999). Biological implications of sulfide in sediment - A review focusing on sediment toxicity. Environmental Toxicology and Chemistry, 18(11):2526-32

Atmospheric fate and pathways

No vapour pressure measurement exists for the submission item but due to the ionic nature of the constituents no relevant release to the atmosphere is expected. Volatilisation can be ignored for metal compounds, except for several organometallic compounds, which are neither present in the submission item nor formed in the environment. Therefore, the Henry coefficient should be set to a very low value. Metals as contained in the submission item may exist in air as suspended particulate matter originating from industrial emissions or erosion of soils. Most of the metal species present in the atmosphere will be bound to aerosols, i.e. the aerosol-bound fraction is almost one.

Metal containing particles are assumed to be mainly removed from the atmosphere by gravitational settling, with large particles tending to fall out faster than small particles. The half-life of airborne particles is assumed to be in the order of days. Some removal by washout mechanisms such as rain may also occur, although it is of minor significance in comparison to dry deposition.

Hydroxylation by indirect photolysis is considered an irrelevant reaction mechanism as no new chemicals would result.

Terrestrial fate and pathways

The Kp values for metals should not be based on the octanol-water partitioning coefficient. Measured partition coefficients should be used instead to describe the sorption of metals to soils. In order to assess the fate of the solid transformation products of the submission item, data from environmental measurements of the sum of the respective metal species were used. These data are influenced by speciation and the speciation behaviour must therefore be accounted for in the derivation of Kp values. The reported Kp values reflect the total metal concentration ratios in equilibrium conditions for all metal compounds occurring under environmental conditions.

Based on measured environmental concentrations, iron is considered immobile or non-mobile with log Kp sediment = 5.08 and log Kp suspended matter = 2.34. Manganese mobility is considered low and the element is characterised as slightly mobile with log Kp sediment = 3.19 and log Kp suspended matter = 1.45 L/kg. Aluminium is considered as moderately mobile with log Kp suspended matter = 2.67.

In conclusion, the submission item is transformed into naturally occurring inorganic, inert compounds after release to the terrestrial environment. These compounds will fill the metal sinks in the soil compartment with no significant influence on bioavailability.

Based on experimental BCF data a metal-typical inverse relationship was established between the water concentrations of dissolved metal and the corresponding BCF in fish (300 to 1 L/kg). The formation of organometallic compounds is not anticipated. Bioaccumulation of the most important metal compounds of the submission item is unlikely. The existing information suggests that iron, aluminium and manganese do not biomagnify. These metals may exhibit biodilution potential at higher trophic levels.

Aluminium is the third-most abundant element in the Earth's crust (7.57% by mass), iron the forth-most (4.7% by mass) and manganese the twelfth-most (0.095% by mass). Manganese and iron are biologically essential metals that are actively taken up by organims. Although these metals are widely distributed in the environment no accumulation in wildlife biota is described in the literature and the available data suggest that organisms are able to adapt to environmentally occurring levels of the metals.

PBT Assessment

According to ECHA (2008) „The PBT and vPvB criteria of Annex XIII to the Regulation do not apply to inorganic substances but shall apply to organo-metals.“ According to REACH Annex XIII as of 31 December 2006 (Official Journal of the European Union, p. L 396/383) „A substance is identified as a PBT substance if it fulfils the criteria in Sections 1.1, 1.2 and 1.3. A substance is identified as a vPvB substance if it fulfils the criteria in Sections 2.1 and 2.2. This annex shall not apply to inorganic substances, but shall apply to organo-metals.“

None of the metals contained in the submission item forms organometallic compounds. Organisms can enrich manganese which may lead to a typical inverse relationship, where the BCF is negatively correlated with the environmental concentration. This is considered a result of metal regulation by the organisms. Manganese is, like the other metals in the submission item, a naturally occurring element which is in equilibrium between bound and bioavailable forms in waters, sediments and soils. None of the other metals in the submission item bioaccumulate to a relevant extent. There is convincing evidence that chronic ecotoxicological threshold levels of all major metals contained in the submission item are > 0.01 mg/L (> 10 µg/L). The natural background concentrations are 66 µg iron species/L, 34 µg manganese species/L, and 50 µ aluminium species/L.

A PBT assessment is obsolete as the criteria are not applicable, no relevant bioaccumulation exist, only low toxicity threshold levels are known and no indication for the formation of organometallic compounds exists.

• ECHA 2008 Guidance on information requirements and chemical safety assessment Chapter R.11: PBT Assessment. 97 p